Grey Relationship Analysis between the Eutrophication Environment Factor and the Density of Phytoplankton in the Different Types of Reservoirs

[Objective] The theoretic reference for the reasonable development and utilization of the water resource of two reservoirs: Hongfenghu Reservoir(broad valley style) and Wujiangdu Reservoir(gorge style) was provided through the research on the main ecological environmental factor such as phytoplankton community and its efficiency.[Method] The character of phytoplankton community and the physicochemical indicator of water-body of two reservoirs in three phases: dry season,wet season and normal season,in the chemical oxygen demand of water in 2005,was investigated and measured,respectively,which data would be analyzed with the method of grey relationship analysis,and main factor affecting the density of phytoplankton in water-body was found out.[Result] The relation degree in two types of reservoirs was more than 0.500 and the order of the factor affecting the density of phytoplankton was transparency demand of oxygen water temperature pH value total N dissolve oxygen total P in Hongfenghu Reservoir and dissolve oxygen water temperaturepH valuetotal Ndemand of oxygentransparencytotal P in Wujiangdu Reservoir.[Conclusion] All of seven factors greatly affected the density of phytoplankton in two types of reservoirs.However,the most important factor was different,and in Hongfenghu Reservoi the transparency was key point,then demand of oxygen,water temperature and in Wujiangdu Reservoir the order of main factor affecting it was dissolve oxgen,water temperature,pH value.